Cooling means for rapid firing guns



May 22, 1945. B. s. ALBERTSON, JR

-COOLING MEANS FOR RAPID FIRING GUNS Filed Aug. '27, 1941 INVENTOR Bfi/JA/v/A/ 5 Azaz-teria/qk ATTORfi Patented May 22, 1945 COOLING MEANS FOR- RAPID FIRING GUN S Benjamin S. Albertson, Jr., Lewes, Del., assignor of forty per cent to Frederick Osann, and twenty per cent to H. Dorsey Spencer, both of White Plains, N. Y.

Application August 27, 1941, Serial No. 408,459

4 Claims.

This invention relates to the liquid cooling of rapid firing or machine guns and has for its general object improvement of the efficiency of the cooling action of liquid cooling means employed with such guns.

Most machine guns which employ a liquid as the cooling medium maintain the liquid in heatexchanging relation to the gun barrel by means of a jacket surrounding the gun barrel, the liquid usually employed being water. This cooling arrangement, without auxiliar equipment, served satisfactorily for cooling machine gun barrels so long as the explosive used in the ammunition was the ordinary black powder and so long as the temperatures developed were the comparatively low temperatures incident to the use of black powder and the low projectile velocities developed thereby. However, with modern high explosives and the high velocities and increased temperatures produced thereby, the cooling effect of the water jacket alone has proved to be inadequate and under field conditions boiling will usuall take place if a sustained fire of not exceeding 100 rounds is fired.

Various attempts have been made to overcome this condition, among which is the attachment of a condenser tube and condenser to the water jacket. This arrangement serves two purposes: First, it is a means of converting the steam back to water, thus serving to conserve the cooling medium, and, secondly, it prevents the appearance of the steam as a small white cloud which would disclose the position of the gun to enemy observ-,

ers. Although the attachment of a condenser permits a slight increase of use of the gun before the cooling means fails to function satisfactorily. it has been found that it does not fulfill its intended purpose much beyond 150 rounds of sustained fire.

Attempts have also been made to increase the eificiency of the cooling system of liquid cooled machine guns by operating circulating means, either by means of the recoil movements of the gun or by means of the gaseous products of the explosion. These means have, however, not been satisfactory in that they have been so constructed and located that they prove to be inefiicient or that they soon cease to function, either by reason of heat damage and corrosion from the hot gases or by reason of their exposed location and their complicated construction.

A particular object of the present invention, therefore, is to provide simple but efficient means for effecting a positive circulation of the cooling medium in a liquid cooled machine gun which will not be liable to injury from the heat or the corro sive action of the gases in the firing of the gun and which will be protected from accidental in- .l y.

A further important object of the invention is to provide means for bringing about a more rapid heat exchange between the cooling liquid and the surrounding atmosphere.

With the foregoing and other objects in view, the invention contemplates utilizing the gas pressure which is generated when the gun is fired to push'a gas piston in one direction against a spring which will serve to return it when the pressure is relieved, thus providing a gas operated motor for a liquid circulating pump. The invention further contemplates so locating this gas-operated motor that it will be surrounded by the circulating liquid and thus protected against the overheating and the gaseous corrosion which have been among the principal drawbacks in the proposed circulating means of the prior art.

Another important feature of the invention is the provision of a heat exchanger which is spaced from but connected with the liquid jacket surrounding the gun barrel, through which heat exchanger the cooling liquid is circulated by the circulating pump and is thus subjected to a more positive and definite cooling action. Still another important feature of the invention is the location of both the gas-operated motor and its connected liquid circulating pump within the heat exchanger aforementioned, whereby not only is the gas-operated motor subjected to the cooling action of the circulating liquid, but both this motor and the circulating pump are protected by the walls of the heat exchanger and by the intervening liquid from accidental injury.

Other objects and important features of the invention will appear from the following description and claims when considered in connection with the accompanying drawing in which Figure 1 is a vertical longitudinal section 7 through the barrel end of a machine gun having the present invention embodied therein;

Figure 2 is a partial section in th same plane showing the pistons of the gas-operated motor and the liquid pump at the ends of their opertive strokes;

Figure 3 is a detail section, similar to Figure 1, showing a slight modification of the intake of the liquid pump;

Figure 4 is a section on the line 4-4 of Figure 1, and

Figure 5 is a similar section showing a slight modification of the heat radiating surfaces of the auxiliary liquid container or heat exchanger.

Figure 6 is a sectional detail showing a modified arrangement of the water intake connection to the auxiliary water container and the exhaust gas connection to the gas operated motor.

In the illustrative embodiment of the invention the machine gun barrel 2, which may be of ordinary construction, is surrounded by a sheet metal jacket 4 for holdingthe cooling liquid in heat-exchanging relation to the outer surface of the barrel 2, but this jacket 4 may be of somewhat smaller diameter than the usual machine gun water jacket by reason of the fact that there is provided an auxiliary liquid container 6, so constructed as to give, with the jacket 4, an overall heat exchanging surface considerably greater than that provided by the water jacket of the ordinary machine gun. The provision of the The auxiliary water container or heat exchanger 6 has an intake connection 8 with the jacket 4 and. av discharge connection for returning the water to the jacket 4, the discharge connection being provided with a check valve 12 which may be impelled to seated position by a sprin M, if this be found to be desirable.

To provide for circulation of the water or other cooling liquid through the jacket 4 and between the jacket 4 and the auxiliary container or heatexchanger 6, a liquid pump and a gas-operated motor for operating this pump are provided, both being-located preferably in the auxiliary liquid container 6 for protection of their operating mechanisms from accidental injury and for preventing the gas-operated motor from becoming overheated. In the illustrative embodiment of the invention the gas-operated motor comprises a piston is, located in a gas expansion cylinder [8 having a gas intake and exhaust connection 20 with the, bore 22 of the gun barrel -2. The piston I is arranged to be moved to the left in Figure 1 against a compression spring 24 abutting against awall 26 through which a piston rod 28, connecting the gas impelled piston is f.-

with the liquid pump piston or plunger 30, extends. The cylinder 32 of the liquid pump may be formed as anextension of the same tube in which the expansion chamber or cylinder l8 for the gas-impelled piston J6 is formed. As shown in Figure 1, the cylinder 32 of the liquid pump is provided with elongated intake ports 34'which, as shown in Figure 2, are barely, closed by the pump piston or plunger 30 at the end of its operative stroke. These ports, therefore, serve both as intake ports and, in com-binationwith the plunger 30, as valve openings to be closed on the operative stroke of the pump.

Fromthe foregoing description, it will be seen that, when the parts are in the. position shown in Figure 1, the ports 34 of the liquid pump will be open and that there will thus. be water between the piston or plunger 30 and the closed end of the cylinder 32. When theprojectile has passed the point where the intake communicates with the bore 22 of the gun barrel 2, the pressure of the propelling gas between the piston l6 and the end of the expansion chamber in the cylinder [8 will drive the piston l6 to the left against the resistance of the spring 24 thus, through the piston rod 28 moving the pump piston or plunger 30 to the left and driving the water by reason of the impact action of the pump piston into the part of the cylinder 32 having a closed end and up through the check valve I2 and discharge I0 into the jacket 4. This will cause water to flow down at the same time through the intake 8. V

As the projectile leaves the gun barrel 2 the gas pressure on the piston I6 will be relieved and the spring 24 will return the piston I6 from its position shown in Figure 2 to its position shown in Figure 1. By reason of the fact that the piston or plunger 30 has only barely closed the intake ports 34 in the cylinder 32, only a very slight movement thereof is sufiicient to uncover the ends thereof to such an extent as to prevent any vacuum action in the closed end of the cylinder 32 from retarding the return stroke of the piston I B.

The form of the invention shown in Figures 1 and 2 avoids the necessity for an ordinary valve and valve seat and thus makes a simplified construction not liable to get out of order. When, however, a more positive pump action is found to be desirable, a check valve and valve seat may be provided in the cylinder 32 in place of the ports closed by the piston or plunger 30. Such a valve is illustrated in Figure 3 and comprises a valve seat 35 and a valve ball 38 impelled into seated position by a spring 40. In the arrangement shown inv Figure 3, the valve 38 will be seated during the operative stroke of the pump and will immediately open against the spring 40 upon the return stroke of the pump.

One of the principal functions of the auxiliary liquid container 6 is its heat-exchanging function. To this end it is provided with as much surface exposed to the air and also in contact with the liquid as is practicable. In the simplest form of the invention illustrated in Figure 4 this extensive heat-exchanging surface is provided by forming corrugations 42 in the wall of the container 6. It will be seen that these corrugations provide an increased surface area both for contact of the air therewith and for contact of the water therewith. In the modified form of the invention shown in Figure 5, heat-radiating fins 44 are provided on a cylindrical wall 46 to give the increased area of heat radiating surface. The last mentioned form of auxiliary container or heat exchanger has the advantage of somewhat greater rigidity and strength when these qualities are desired, although it does not provide so much contact surface for the water.

From the foregoing description it will be seen that except for a short exposed section of the gas intake and exhaust 20 which, if it were found to be desirable, might be surrounded by the water intake 8, as shown in Figure 6 of the drawing,

all parts of the gas-operated motor for driving the liquid pump are water cooled and .thus not liable to injury from overheating. It will also be seen that all the movable parts of both the gasoperated motor and the liquid pump are enclosed within the walls of the auxiliary Water container f6 andare thus protected from accidental injury and distortion both by these walls and by the water interposed between the walls and the cylinders l8 and 32.

What is claimed as new is:

1. In cooling means for rapid firing guns, the combination with the gun barrel and a jacket for maintaining any suitable cooling liquid in heat exchanging relation to said gun barrel, of a gas operated motor comprising a piston cylinder for a gas piston having a gas intake communicating with the bore of the gun barrel, a gas piston in said cylinder, a spring so arranged in said cylinder as to be deflected by the operative stroke of said piston and thus rendered operative to return said piston to its initial position when the impelling gas pressure is relieved, a liquid pump housing, liquid propelling means therein, connections between said gas piston and said liquid propelling means whereby the movements of said gas piston are operatively transmitted to said liquid propelling means, said liquid pump housing being provided with an intake port for receiving cooling liquid to be circulated and with a discharge port communicating with the interior of said jacket and means for positively guiding cooling liquid to be circulated to the intake port of said pump housing, said means being so constructed and arranged that it receives cooling liquid, which has been maintained in said jacket in heat exchange relation to said gun barrel, from a part of said jacket remote from the aforementioned liquid pump discharge port and that it encloses said gas operated motor and said liquid pump therewithin and also within any cooling liquid circulated therethrough.

2. Gun cooling means according to claim 1 in which the means for positively guiding the cooling liquid to be circulated to the intake port of the liquid pump housing comprises a second container for the cooling liquid connected to said jacket, shaped to provide extensive air-exposed heatexchanging surfaces and enclosing both the gas operated motor and the liquid pump therewithin and within any cooling liquid circulated therethrough.

3. Gun cooling means according to claim 1 in which the means for positively guiding cooling liquid to be circulated to the intake port of the liquid pump housing comprises a second container for cooling liquid having its Wall corrugated lengthwise both to reinforce it structurally and to provide an extensive heat exchanging surface, said second container enclosing both the liquid pump and the gas operated motor within said corrugated wall and within any cooling liquid circulated therethrough.

4. Gun cooling means according to claim I having, as a part thereof, an auxiliary container and heat exchanger for cooling liquid in which both the gas operated motor and the liquid pump are enclosed and having an intake connection to said container from said jacket so spaced both from the intake port to the liquid pump housing and from the discharge port therefrom as to insure circulation of cooling liquid both throughout said auxiliary container and throughout said jacket, the gas intake to said gas motor from the gun barrel being enclosed within said intake connection from said jacket to said auxiliary container.

BENJAMIN S. ALBERTSON, JR. 

